retaining boundary

In my slightly sloping garden I want to create a terrace which will require a low, 500mm, step up.
obviously a low wall in brick is possible but what are those cage thingys called that can be filled with different rocks?

 

C-Kev,they are called 'Gabions'

 

thanks Paladin much obliged

 

Hey Paladin
How'd ye know that?

 

I read the same in the current issue of " Grow your own veg " magazine !